Valve-operating mechanism



SePt- 24, l929- 4 A. F. scHwENDNER 1,729,458

VALVE OPERATING MECHANISM Filed Aug. 9, 1927 2 Sheets-Sheet l INVENTOR mAJ?. Sahwenclner BY Q 0?; M

ATTORNEY Sept. 24, 1929. A, F, SCHWENDNER 1,729,458 l VALVE OPERATINGMECHNIS Filed llg. 9, 1927 2 ShOtS-Sheet 2 ATTORNEY A INVENTORE5chwe-ndnr an. M

Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE ANTHONY F.scHwRNnNER, OF EssINGToN, TENNsYLvANIA, AssreNoR To WEST- rNeHoUsRELECTRIC a MANUFACTURING COMPANY, A CORPORATION or PENN- SYLVANIAVALVE-OPERATING- MECHANISM Application iled August 9, 1927. Serial No.211,775.

My invention relates to a governing system for prime movers, and it hasfor its object to provide a governing system embodying therein athrottle valve controlling the admission of motive fluid to the primemover which is automatically closed upon the occurrence of conditionsmaking further Operation of the prime mover unsafe or undesirable.

Another object is to provide a governing system embodying a fluidpressure governor and a throttle valve which is automatically closedupon failure of fluid pressure in the governing system.

Another object is to provide a governing l5 system embodying a throttlevalve which is biased to closed position and is opened in opposition tosaid bias by means operated di-y rectly by the prime mover shaft.

A further Object is to provide a governing system for a prime moverwhich will not permit the prime mover to be started until thelubrication system of said prime mover is placed in operation.

Still another Objectis to provide a throttle valve operating mechanismwhich will not allow the throttle valve to be opened too rapidly.

In accordance with my invention, I provide a throttle valve connected toa piston or other biasing means, is applied to the piston, or to thevalve or the connection between the two, to urge the valve to closedposition.

Fluid pressure is used in the fluid pressure :r governor and it isadmitted to the cylinder to act upon the piston to open the valve in oposition to the pressure of the spring. eans are further provided forretaining the valve closedwhen it has Once tripped until the throttlevalve is opened slowly and intentionally.

Apparatus e emplifying my invention is illustrated in tl e accompanyingdrawings, `in which Fig. 1 is a diagrammatic View, with parts insection, of one embodiment; and

Fig. 2 is a diagrammatic view, with parts in section, of anotherembodiment.

Referring to the drawings in detail, I show, at 10, the throttle valveof a prime mover,

operating in a suitable cylinder. A spring,

for example, a steam turbine. From the throttle valve 10 the motivefluid, in this case steam, is transmitted through a conduit l1 to thegovernor controlled valve 12, from which 1t may be admitted to thenozzle chamber of the steam turbine.

The 1prime mover embodies a shaft 13, upon W 1ch is mounted an impeller14. The impeller 14 rotates in a pump housing 15, forming therewith thepump 30. The fluid pressure developed by the pump 30 is proportional tothe speed of rotation of the shaft 13.

I preferably use lubricating oil as the medlum of fluid pressure in mygoverning system, but it will be apparent that other fluids,particularly liquids, may be used.

The lthrottle valve 10 is operated by a valve operating mechanismindicated at 17, conslsting, generally, of a piston 18, connected to thevalve 10 as by a rod or stem 19, and a cylinder 21. Any suitable meansis provided for exerting a force on the valve or the valveoperatingmechanism in the direction to close the valve. I show a compressionspring 22 for this purpose, which is interposed between the upper end ofthe cylinder and the upper side of the piston, and which closes thevalve 10 in the absence of sufficient opposing force.

An axially-extending passage 23 is formed in the valve stem 19, andextends from the upper end thereof to a point immediately below thepiston 18 where it communicates with the interior of the cylinderthrough a radiallylextending portion 23. The upper gud of the 'passageforms a port designated A screw stem 25, is disposed in axial alignmentwith the valve stem 19, and the lower end thereof abuts against theupper end of the'valve stem .and closes the port 24 upon sufficientdownward movement of the screw stem. The stem 25 is adapted to be raisedand lowered by means of a handwheel 26 attached to the upper endthereof.

Fluid pressure developed by the pump 30, and transmitted through thepipes 27 and 28, is communicated to the lower end of the cylinder I21through an opening 29, and acts on the lower side of the piston 18 toOpen the throttle valve. The cylinder 21 is also provided with adischarge ort 21' which is disposed above the upper imit of travel ofthe piston 18.

A valve 31 is interposed between the pipes 27 and 28. As may be seenfrom Flgl. 1, this valve operates in a valve casing 32, aving a port 33communicating with .the conduit 27, and a port 34 communicating with-the conduit 28. The valve casing 32 also communicates at its lower endwith a d rain yconduit 35. The valve `31 is provided wlth pistonportions 36, 37 and 38. The piston portions 36 and 37 are so disposedthat the space therebetween is always in communication with the port 33during the full travel of the valve. The piston portion 37 is sodisposed that 1t will be immediately below the port 34 when the valve isin its lowermost position to provide communication between the ports 33and 34, and so that it will be immediately above the port 34 when thevalve is in the upper end of its travel, when communication of the port34 with the port 33 is cut oi and the port 34 is placed in communicationwith the drain conduit 35.

A spring 39, at the lower end of the valve casing 32, urges the valve 31upwardly. The

valve 31 is normally held at the lower end of its travel by a lever 41,pivoted at 42 to a stationary member, such as a bracket of the valvecasing 32. The lever 41 is normally held at its ree end by the arm 43 ofthe auto-stop mechanism 44. The arm 43 is adapted to be moved out ofengagement with the lever 41 upon the weight 45 striking the p arm 46,which is connected to and moves the A restricted orifice 27 is providedin the conduit 27 near the end communicating with the valve casing 32,and restricts the: dow of fluid to the throttle valve operatingmechanism 17. n

A governor 51, operating the valve 12, consists of a casing 53, anoperating piston 54 and a pressureresponsive pilot valve 55. Thegovernor 51 is controlled and operated by the tluid pressure developedby the pump 30, which is transmitted through conduits 27 and 52 to thelower end of the casing 53. The piston 54 is provided with an uppertubular extension 56 and a lower tubular eXtension 57. A cylinderextending through the portions 56 and 57 and through the piston itselfis formed in the interior thereoi'. rlhe pilot valve 55 which has ahollow interior and a closed upper end 68, is disposed within thecylinder and controls the movements otl the operating piston. Theoperating lpiston 54 is provided at the interior cylindrical surfacewith an annular series of ports 58, which open into the upper end of thepiston 54. A similar annular series of ports 59 communicates with thelower end of the piston 54. The pilot valve 55 is provided with recessedportions 61 and 62, forming a piston portion 63 therebetween. A seriesof ports 64 provides communication between the recessed portion 61 andthe hollow interior of the pilot valve 55.

A sprin' 65 is disposed within the hollow interior of the pilot valve,being secured at its lower end to a spring-holding member 66 fastened tothe casing 53, and at its upper end to a spring-holding member 6 carriedby the closed upper end 68 of the pilot valve. The closed upper end 68is provided with a restricted opening 69, permitting a restricted Iiowof fluid therethrough.

The upper tubular extension 56 of the operating iston 54 is providedwith openings 71, whic are disposed so as to be above the pilot valve 55at all times. The casing 53 is provided with an upper extension 72having a recessed portion 73 which is sufficiently elongated tocommunicate with the openings 71 at all times. A conduit 74 communicateswith the recessed portion 73, and has a backpressure valve 75 interposedtherein. The

valve 75 may be adjusted to any desired back pressure.

The upper end of the operating piston 54 is pivoted to a link 76, whichis pivoted at its other end to one end of the lever 77. The lever 77 ispivoted to a stationary bracket 78 intermediate its ends, and the otherend is connected to the Valve stem 79 of the valve 12 through a link 81.The valve 12 is urged to closed position by any suitable means such as acompression spring 82, acting against a collar 82 on the valve stem 79.

An auxiliary pump 83 is driven by a small turbine 84, and develops aiiuid pressure which may be communicated to the conduit 52 through aconduit 84. A check valve 85 is interposed in the conduit 84 whichpermits bine 84 is controlled by a hand valve 86.

A check valve 87 in the conduit 27 permits delivery of fluid pressurefrom the pump 30 hut prevents escape of fluid pressure to the latterwhen idle. l

The operation of this embodiment of my invention is as follows: l

Assuming the prime mover to be idle, it is necessary to provide iluidpressure from a source other than the impeller 14 in order to open thethrottle valve 10. The hand valve 86 is therefore opened, therebyadmitting motive fluid to operate the small turbine 84, which drives theauxiliary pump 83. 'lhe fluid pressure developed by the pump 83 istransmitted through the conduits to the gov- Cil ment by the screw stem25, and it is therefore necessary. to raise the stem by turning thehandwheel 26. As the stem 25 is raised, the fluid pressure beneath thepiston 18 raises the piston and causes it to follow the screw stem` 25.During such movement the stem 25 vcloses the port 24, and therebyprevents escape of fluid pressure through the passage 23 into the spaceabove the piston 18. The throttle valve 10 is thereby opened and motivefluid is admitted therethrough to the conduit 11, through which it flowsto the governor valve 12.

The speed with which the throttle valve is opened is limited by the rateof oil flow through the orifice 27. If the stem 25 is raised at a higherrate, it uncovers the ort 24, and the oil pressure escapes through t epassage 23, allowing the spring 22 to shut the throttle valve 10. Thisis desirable to prevent racing of the prime mover in starting,especially in the case of a turbo-generator which is started withoutload. To close the throttle valve 10, the handwheel 26 is turned tolower the stem 25, which forces the piston 18 downwardly against thefluid pressure.

The fluid pressure developed by the auX- iliary pump 83 is alsocommunicated to the governor 51 and admitted through the ports 64 to therecessed portion 61 of the pilot valve. Upon starting, the pilot valve55 is in a lower position than that shown in the drawing due to theaction of the spring 65, and the fluid pressure, therefore, flowsthrough the ports 58 to the upper side of the piston 54 and acts thereonto lower the piston and to open the valve 12.

The fluid pressure developed by the auX- iliary pump 83 is less thanthat developed by the main impeller 14 at or near operating speed, and,therefore, as the prime mover comes into operation and approaches itsnormal operating speed, the pressure developed by the pump 30 exceedsthe pressure developed by the auxiliary pump 83. The supply of motivefluid to the small turbine 84 is shut off by any suitable means such asthe hand valve 86 and the escape of fluid pressure through the conduit84 is prevented by the check valve 85.

The pressure developed by the pump 30, which is a function of the speedof the prime mover, acts on the pilot valve 55 against the tension ofthe spring 65. A. restricted flow of this fluid pressure is permittedthrough the restricted opening 69, and passes throu h the openings 71and the recessed portion g3 to the conduit 74. The back pressure valve 75'is adjusted to a desired pressure, and imposes a back pressure uponthe fluid flow therethrough. It will be apparent therefore that there isa pressure on the upper side of the pilot valve 55 which cooperates withthe spring 65 to oppose and balance the fluid pressure beneath the pilotvalve,

As the speed of the prime mover approaches the desired operating speedthe pilot valve 55 is raised until the governor valve 12 is brought tothe proper position.

i Theaction of the pilot valve in controlling the piston is as follows:As the speed of the prime mover increases, the fluid pressure acting onthe pilot valve 55 increases and raises the pilot valve. This places theports 58 and 59 in communication with the recessed portion 62. The fluidabove the piston 54 may therefore flow to the lower side thereof, suchow being brought about by the action of the springv82 and the oilpressure on the lower end of the lower tubular extension 57, which tendto close the valve 12 vand to move the operating piston 54 upwardly.This movement continues until the ports 58 are covered by the pistonportion 63 when movement of the operating piston ceases.

Upon an increase of load on the prime mover, resulting in a reducedspeed thereof, theresulting reduced pressure on the pilot valve 55permits the spring 65 to lower the pilot valve. This movement uncoversthe ports 58 and places them in communication with fluid pressurethrough the recessed portion 61 and the ports 64. The operating pistontherefore moves downwardly to open the valve until the ports 58 areagain covered by the piston portion 63.

The auto-stop mechanism for closing the throttle valve in case the primemover exceeds a certain predetermined speed, generally 10% above thenormal operating speed, operates as follows:

Upon the .predetermined speed being attained, the weight 45, whosecenter of gravity is offset from the axis of the shaft 13, fliesoutwardly and strikes the arm 46, which, in turn, moves the arm 43 outof engagement with the lever 41. The valve 31 is then moved upwardly bythe force of the spring 39, the piston portion 37 moving upwardly abovethe port 34. The supply of fluid pressure from conduit 27 to thethrottle valve operating mechanism 17 is now cut olf and the conduit 28is in communication with the drain conduit 35. The fluid pressure in thecylinder 22 beneath the piston 18 is released and the piston 18 islowered by force of the compression spring 22. The escape of the fluidbeneath the piston 18 is further accelerated by the passage 23, which isopened as the piston leaves the screw stem-25. Downward movement of thepiston 18 continues until the throttle valve 10 is closed.

It is important that the throttle valve 10 be not opened suddenly orunintentionally, such as might be done by resetting the valve 31. Thisis accomplished by the passage 23. Should the valve 31 be reset withoutlowering the screw stem 25, the fluid pressure admitted to the cylinder21 would escape through the passage 23 and would not raise the piston18. It is therefore necessary to lower the stem 25 until the port 24 isclosed. The throttle valve may then be opened by raising the stem 25,which permits the fluid pressure beneath the iston 18 to move the sameupwardly followmg the stem 25.

The restricted orifice 27', in limiting the oil flow to the throttlevalve operating mechanism, prevents loss of pressure in the conduit 27,should the valve 31 be reset before the stem 25 is lowered to close theport 24.

Inasmuch as the throttle valve is opened only by pressure in thegoverning system, it will be seen that, should such pressure fail, theprime mover is shut down. This 1s true even though the failure be butmomentary, for the reason that when the piston 18 once moves down awayfrom the stem 25 the port 24 is uncovered and the ressure beneath thepiston escapes through t e passage 23. The prime mover cannot again beplaced 1n operation until the fluid pressure is restored.

In Fig. 2, I show a modification of my invention wherein the lubricationsystem is embodied with the governing system, the lubricating oil beingused as the medium of :Huid pressure. This modification also embodiesother developments of the governing system as applied to prime movers. i

The throttle valve 10 is controlled by a valve-operating mechanism 17identical with that described in connection with the embodiment shown inFig. 1. The pump 30 is also identical with that shown in Fig. 1.

Oil pressure for operating the mechanism 17, is supplied, as before,from the oil pressure in the governing system, in this case beingsupplied through a restricted orifice 126 and conduits 127 and 128. Theconduit 128 communicates with a valve 129, which is normally closed.When opened, the valve 129 releases the oil pressure in the conduit 128,and permits the oil to ow to a drain conduit 130.

The valve 129 is normally held in closed position by an auto-stopmechanism indicated generally at 131, which includes a lever 133 pivotedat 134 for holding the valve closed, a bell crank lever 132 engaging thelever' 133, and a governor weight 45 disposed in a diametrical openingin the prime mover shaft 13.

l The governor valve 12 is controlled by an oil pressure governorsomewhat diierent in detail. The valve stem 91 of the governor valve isdirectly connected to a piston 92 operating in a cylinder 93. Oilpressure for operating the piston 92 is supplied through conduits 94 and95 from ports 96 and 97 of a relay valve 98. The relay valve 98comprises a casing 99 and a pilot valve101. The pilot -valve 101 isprovided with piston portions 102 and 103 which normally cover the ports96 and 97, respectively, and with piston portions 104 and 105 at theupper and lower ends thereof, respectively.

The relay valve is supplied with oil pressure from the pump 30 throughconduits 106 and 107, the latter communicating with the port 108 whichis always in communication with the space between the piston portions102 and 103. The valve casing 99 is further provided with dischargeports 109 and 111 which communicate with the space between the pistonportions 104 and 102, and with the space between the piston portions 103and 105, respectively. These ports communicate with a drain conduit 112.The pilot valve 101 is formed with a hollow interior and a closed upperend 113. The closed end 113 has a restricted opening 114 therein.

A tension spring 184 is disposed within the hollow interior of the pilotvalve 101, the upper end being secured to the closed end 113, and thelower end being secured to the upper end of a stem 185. The stem 185extends through the valve casing 99, the lower end being pivoted,through `a short link 186, to a lever 187, intermediate the ends of thelatter. The lever 187 is pivoted at one end to a stationary part 188,and at the other end to the valve stem 91. I

Oil pressure from the pump 30 is transmitted directly to the lower endof the casing 99 through a conduit 115, which does not communicate withany other conduit. A conduit 116 communicates with the upper end of thecasing 99 and receives the oil passing through the restricted opening114. The escape of oil through the conduit 116 is normally controlled bythe back pressure valve 117. The valve 117 is adjustable, whereby a backpressure of any desired value may be imposed on the oil flowing throughthe conduit 116 and upon the oil above the pilot valve 101. The oilreleased by the backpressure valve is discharged into a drain conduit118.

lln this modilication, an oil reservoir 119 is disposed at a level belowthe pump 30, and is adapted to receive the lubricating oil dischargedfrom the bearings 121 and 122 through the conduits 123 and 118. Anejector 124 is disposed below the reservoir 119, and the oil in thereservoir 119 ows to the entraining chamber of the ejector by gravity.The ejector is supplied with oil under pressure from the pump 30 throughthe conduits 106, 107 and 125. This oil under pressure entrains oil fromthe reservoir and supplies the same to the conduit 120 at a lowerpressure, for example 5 pounds per square inch. The conduit 120 suppliesoil to the bearings 121 and 122. This conduit also supplies oil to theinlet .of the pump 30, which is therefore supplied with oil underpositive pressure.

A trip mechanism 151 is provided, for releasing the pressure above thepilot valve 101 upon a failure of the bearing oil ressure. This tripincludes a valve 152, an a valve casing 156, having a port 153communicating with the upper end of the valve casing 99 through theconduit 116, and having a discharge port 154 communicating with thedrain conduit 118 through a conduit 155. The valve 152 is controlled bya iston 166, preferably integral therewith, an subjected on its lowerside of the pressure in the chamber 157 formed in the lower end of thecasing 156. The piston 166 is urged in the direction to open the valve152 by a spring 167.

Bearing oil pressure is-transmitted from the conduit 120 to the chamber157 through a conduit 171, a restricted orifice 172, and conduits 169and 168.

The conduit 169. also communicates with the conduit 127 through a checkvalve 174 and a conduit 173. The check valve 174 opens to permit iowfrom the conduit 169 to the conduit 173, but prevents flow in theopposite direction.

An auxiliary oil pump 175, disposed in the bottom of the oil reservoir119, is provided for maintaining oil pressure when the pump 30k docs notprovide sutlicient pressure; that is, in starting and shutting down theturbine. The auxiliary pump 175 discharges to the conduit 125 throu h aconduit 176, having a check valve 177 giisposed therein to preventrelease of oil pressure in the conduit 125 when the .same exceeds thepressure developed by the auxiliary pump or when the auxiliary pump isnot in operation. The auxiliary pump. 17 5 is driven by the smallturbine 178, provided with motive fluid, such as steam, through aconduit 179, in which a hand valve 181 is preferably disposed. Theadmission of motive Huid to the turbine'178 is further controlled by apressure governor 182, in response to the bearing oil pressure which istransmitted thereto through the conduit 183 from the conduit 171.

A check valve 183 is provided in the con duit 106 to prevent vtherelease of oil pressure through the main pump 30 when the auxiliary pump175 is in operation.

The operation of the above described embodiment is as follows:

To start the turbine it is necessary to have oil pressure to open thethrottle valve 10. The hand valve 181 is therefore opened and steamadmitted to the turbine 178, whereupon the auxiliary pump 17 5 builds upoil pressure which is transmitted to the conduit 125, and from there toother parts of the system. It flows through the conduit 107, the orifice126, and conduits 127 and 128 to the cylinder 21, in which it isavailable for opening the throttle valve.

If the stem 25 is not in its lowermost position, the port 24 is open andthe oil escapes through t e passage 23. The stem 25 is therefore loweredby the handwheel 26 so that the lower end thereof abuts against thevalve stem 19 and closes the port 24. The stein 25 is then raised,whereupon oil pressure raises the piston 18 to o en the throttle valve.

T e release o the pressure developed by the. auxiliary pump to the mainpump 30, which has not yet come into operation, is prevented by thecheck valve 183.

When o il ressure is established in the conduit 125, 1t 1s supplied tothe ejector 124 for motlvatin the same, and the latter su plies oilthroug the conduit 120 to the in et of the main pump 30 and to thebearings 121 and As the bearing oil pressure is established in the4conduit 120, it 1s communicated to the chamber '1.57 where it moves thepiston 166 1n opposition to the spring 167 to close the valve 152. Theonly escape for oil from the conduit 116 is now through the valve 117,which imposes a back pressure on the oil in the conduit 116 and 1n theupper end of valve casing 99 above the pilot valve 101.

The oil pressure established in the conduit 125 is also transmittedthrough the conduit 107 to the inlet port 108 of the relay valve 98 foractuating the governor piston 92. Such pressure, however, is not appliedto the lower end of the pilot valve 101, and the latter is thereforeheld in its lowermost position by the spring 184. The port 108 istherefore in communication with the port 97, and oil pressure istransmitted through conduit 95 to the lower side of therpiston, 92, andactuates the same to open the governor valve 12. Motive Huid now flowsthrough the throttle valve and the governor valve 12 -to the prime moverto operate the same. The shaft 13 is thus rotated and the pump 30 beginsto build up oil pressure. As the prime mover approaches its operatingspeed, the pressure developed by the pump exceeds the pressure developedby the auxiliary pump 175. The check valve 183 therefore opens and thecheck valve 177 closes. A higher pressure is also transmitted to theejector 124, causing a resultant increased bearing oil pressure in theconduit 120, and also in the conduit 171. The auxiliary pump governor182 is so designed that as the bearing pressure increases in accordancewith the pressure developed by the pump 30, the governor 182 shuts offthe admission of motive liuid to the turbine 178.

The pressure developed by the pump 30 is transmitted through the conduit115 to, the relay valve 98, and is applied to the lower end of the pilotvalve 101 in opposition to the force of the spring 184. The restrictedorifice 114 permits a restricted flow of oil therethrough, and theescape of this oil is controlled by the valve 117, which-imposes a backpressure thereon. The pilot valve 101 is thus subjected to this backpressure on the upper end thereof. The purpose of the back pressure isto permit a lighter spring 184 havthe pilot valve 101. The oil pressurebeneath ing a suicient scale; also 'to providea speed changer forcontrollingthe speed or load of the prime mover.

As thevprime mover attalns its operating 'speed the governing oilpressure increases and t e ilot valve 101 moves upwardly to control t eports 96 and 97.

The oil governor controls the valve 12 during normal variations in loadand speed as follows:

Upon an increase in load and a resultant decrease in speed the governingoil pressure is reduced, causing the pilot valve 101 to be lowered fromthe position shown in the drawing. Oil pressurey from the port 108 nowlHows to the port 97 and to the lower sideof the Apiston 92. The port 96is 1n communication with the discharge port 109, permitting thedischarge of the oil above the piston 92. The valve 12 is thereforemoved upwardly 1n opening direction. At the same time the lever 187moves upwardly, permitting the pilot valve 101 to move upwardly untilthe ports 96 and 97 are again closed. I

Upon a decrease in load and increased speed, the oil pressure isincreased and ralses the pilot valve 101. The port 96 1s now 1ncommunication with the oil pressure supply port 108 and the port 97 withthe discharge port 111. The valve 12 is therefore moved' in closingdirection until the pilot valve 101 is lowered to normal positionthrough the lever 187.

Suppose that, for some reason, the speed of the prime mover increases tomore than a predetermined overspeed, usually 10% above normal speed. Theautostop governor weight 45, whose center of gravity is offset from theaxis of the shaft 13, iiies outwardly and strikes the lever 132, which,in turn, disenages the lever 133. The lever 133 is now ree to move aboutthe pivot 134, permitting the valve 139 to open under pressure of theoil in the conduit 128.

The oil pressure in the conduit 128 and in the `cylinder 21 below thepiston 18 is therefore released, whereupon the spring 22 moves thepiston 18 downwardly to shut the throttle valve 10, in the same manneras described in connection with Fig. 1.

The restricted orifice 126 permits the escape of some oil from thehigh-pressure conduit 107, but prevents the loss of suicient oil todestroy the pressure therein.

When the pressure in the conduit 128 is released, the pressure in thechamber 157 is also released through the check valve 174 and thecommunicating conduits, the check valve opening in this direction. Therestricted oriice 172 prevents the escape of sufcient oil into theconduit 169 to destroy the bearing oil pressure. The valve 152 istherefore opened, permitting the release of the pres sure in the conduit116 and in the space above the latter readilyr overcomes the spring 184and moves the pllot valve upwardly, causing a closing of the governorvalve 12.

When the cause ofthe overspeeding has been remedied, the auto-stopmechanism 131 is reset, closing the valve 139. The stem 25 is lowered toclose the port 24. Oil from the conduit 107 now flows slowly through theorifice 126 to the cylinder 21, and the piston 18 may be raised byraising the stem 25.

The check valve 174 closes upon restoration of oil pressure in theconduit 173, which is greater than the bearing oil pressure in theconduit 169. The oil pressure in the chamber 157 is also restored byflow of oil through the orifice 172, and the valve 152 is closed,permitting normal operation of the governor.

Assume now that the bearing oil pressure fails, an event unlikely tooccur with the present arrangement. although it is possible. Thepressure in the chamber 157 would drop, opening the valve 152, andcausing closing of the governor valve 12 in the manner described above.The pressure governor' 182 would also admit motive fluid to the smallturbine 178 for driving the auxiliary oil pump 175, which would providehigh-pres,- sure Huid to motivate the ejector 124.

It will be seen from the above description, that I have connected thethrottle valve operating mechanism with the fluid pressure governingsystem in such manner that opening of the throttle valve is at all timesdependent upon fluid pressure in the governing system. Should a failureof Huid pressure ocour, the throttle valve is closed and cannot again beopened until fluid pressure is restored and then only after thehandWheel which controls the throttle valve is brought down to closingposition of the valve. It Will thus be apparent that the safety of theprime mover is substantially increased.

While I have shown my invention in two forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modilications, without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are imposed by the prior art or as arespecifically set forth in the appended claims.

What I claim is:

1. The combination with a prime mover having a valve for regulating theadmission of motive fluid thereto and a throttle valve Varranged inseries with the regulating valve,

prising means providing a fluid for opening ythe throttle valve inopposition to said bias. l

2. The combination with a prime mover f having a valve for regulatingthe admission of motive fluid thereto and a throttle valve arranged inseries with the regulating valve, of a governing system for said valvescomprising means operated by the prime mover for developing a fluidpressure varying as a function of the speed of the primemover, means foractuating said regulating valve in response to said fluid pressure,means for biasing said throttle valve to closed position, means forapplying fluid ressure from said first-mentioned means or opening thethrottle in opposition to said bias, and means responsive toapredetermined overs eed: of the prime mover for releasing the flu1dpressure in the last-named means to bias to close the throttle valve.

3. The combination with a prime moverhaving a valve regulating theadmission ofy motive fluid theretovand a throttle valve arranged inseries Withthe regulating valve, of f a governing system for said valvescompris,- ing an impeller mounted on a shaft of said prime moveranddeveloping a fluid pressure varying as a function of the speed of theprime mover, means for operating the regulating valve in response tosaid fluid pressure, means biasing the throttle valve to closedposition, means for applying fluid pressure developed by said impellerto open the throttle valve in opposition to said bias, and meansresponsive to an abnormal operating condition of the prime mover forreleasingl the fluid pressure in the last-named means to permit saidbias to close the throttle valve. 4. The combination With a prime moverhaving a valve for regulating the admission of motive fluid thereto anda throttle valve arranged in series with the regulating valve, of agoverning system for said valves comressure varying as a .function ofthe spee of the prime mover including fluid-pressure-developing meansoperated bythe prime mover,

a fluid pressure relay controlled in response to said variable fluidpressure and actuated, by fluid pressure develo ed by thefluid-pressure-developing means or actuating the regulating valve, aspring for biasing the throttle valve to closed position, means for aplying fluidpressuredeveloped by said Ifluidpressure-developing meansfor opening the throttle valve in opposition to the bias of said spring,and means responsive to a predetermined overspeed of said prime moverfor releasing the fluid pressure in said last-flamed means.

In testimony whereof, I have hereunto subp scribed my name thisfirst'd'ay of August, 1927.

ANTHONY F.` soHWENDNER. 'j

permit said

